1. Field of The Invention
The present invention relates to a corrosion protection composition for the production of anticorrosion coatings on metal workpieces for storage until installation, the composition being based on a wax that is dissolved in a solvent.
2. Description of The Related Art
Corrosion protection compositions used for the production of anticorrosion coatings on metal workpieces are used, in practice, primarily for the time period between their manufacture and their installation. Such compositions are preferably composed of mineral waxes or fats that are dissolved in highly volatile solvents. The metal workpieces, after manufacture, are dipped into the corrosion protection solution and the highly volatile solvent(s) evaporated to form a protective coating on the workpieces. Then, if necessary, the coatings may be removed before installation of the workpiece, for example, by dissolving them away, washing them off, or melting them off.
According to its intended use, the corrosion protection composition should wet the workpiece, which may have a very complicated geometrical structure, so as to form the most uniform possible, thick coating layer. This helps insure that the corrosion protection properties of the coating are sufficient to last over long periods of time during storage of the workpiece. The coating must adhere well to the workpiece; it must not stick to other workpieces or the workpiece's packaging; it must not soak into the packaging material; and, when the workpiece is installed, there must be no chemical reaction with the installed partners, i.e., mating structures.
The conventional, highly volatile solvents used in such corrosion protection compositions are chlorinated hydrocarbons, such as trichloroethylene or perchloroethylene which, although easily managed because they are non-combustible liquids, are a health risk and, according to present rules and regulations, can be employed only with costly and extensive protective measures.
For example, European Patent 0,122,762, teaches a wax-containing corrosion protection composition dissolved in a solvent composed of a mixture of petroleum and aromatic hydrocarbons. Aromatic hydrocarbons, however, also present a considerable health risk so that these corrosion protection compositions must also be employed with costly and extensive protective measures and, in addition, other expensive safety measures are necessitated by the combustibility of these solvents.
Originally, as disclosed, for example, in German Patent 717,967, mineral fats, vaseline, paraffins or waxes were melted to form "hot fat" immersion baths and were employed directly to produce anticorrosion coatings. An anticorrosion coating was produced by dipping the workpieces directly into the melt. Handling of such hot fat immersion baths is a difficult operation, however. Moreover, prolonged heating of such melt baths causes oxidation products to be formed from the substances employed including aggressive oxidation products whose vapors are basically just as harmful as certain solvent vapors. Finally, the substances become useless over the course of time. Moreover, the resulting coatings frequently do not have the required operational characteristics. They became too viscous or thick and chipped off due to lack of adhesion and as a result of brittleness.
It is therefore an object of the present invention to provide a corrosion protection composition based on a solution of wax in a solvent which, while easily handled, produces anticorrosion coatings on metal workpieces made of, for example, cast iron or steel, that have desirable operational characteristics and provide corrosion protection for the workpieces during storage until installation without presenting a health risk.